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Start date: 2010End date: 2019Subject: search.filters.subject.HumansAuthor: search.filters.author.Salmas, Ramin EkhteiariAuthor: search.filters.author.Yurtsever, MineHas files: Yes

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    PublicationOpen Access
    Investigation of inhibition mechanism of chemokine receptor CCR5 by micro-second molecular dynamics simulations
    (Nature Publishing Group Houndmills Basingstoke, Hampshire RG21 6XS, 2015) Salmas, Ramin Ekhteiari; Yurtsever, Mine; Durdağı, Serdar; Salmas, Ramin Ekhteiari, Department of Chemistry, İstanbul Teknik Üniversitesi, Istanbul, Turkey; Yurtsever, Mine, Department of Chemistry, İstanbul Teknik Üniversitesi, Istanbul, Turkey; Durdagi, Serdar, Department of Biophysics, Bahçeşehir Üniversitesi, Istanbul, Turkey
    Chemokine receptor 5 (CCR5) belongs to G protein coupled receptors (GPCRs) and plays an important role in treatment of human immunodeficiency virus (HIV) infection since HIV uses CCR5 protein as a co-receptor. Recently, the crystal structure of CCR5-bound complex with an approved anti-retroviral drug (maroviroc) was resolved. During the crystallization procedure, amino acid residues (i.e., Cys224, Arg225, Asn226 and Glu227) at the third intra-cellular loop were replaced by the rubredoxin for stability reasons. In the current study, we aimed to understand the impact of the incorporated rubredoxin on the conformations of TM domains of the target protein. For this reason, rubredoxin was deleted from the crystal structure and the missing amino acids were engineered. The resultant structure was subjected to long (μs) molecular dynamics (MD) simulations to shed light into the inhibitory mechanism. The derived model structure displayed a significant deviation in the cytoplasmic domain of TM5 and IC3 in the absence of rubredoxin. The principal component analyses (PCA) and MD trajectory analyses revealed important structural and dynamical differences at apo and holo forms of the CCR5. © 2015 Elsevier B.V., All rights reserved.
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    PublicationOpen Access
    The signaling pathway of dopamine D2 receptor (D2R) activation using normal mode analysis (NMA) and the construction of pharmacophore models for D2R ligands
    (Taylor and Francis Ltd. [email protected], 2017) Salmas, Ramin Ekhteiari; Stein, Matthias Jeanette; Yurtsever, Mine; Seeman, Philip; Erol, Ismail; Mestanoglu, Mert; Durdagi, Serdar; Salmas, Ramin Ekhteiari, Department of Biophysics, Bahçeşehir Üniversitesi, Istanbul, Turkey; Stein, Matthias Jeanette, Molecular Simulations and Design Group, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany; Yurtsever, Mine, Department of Chemistry, İstanbul Teknik Üniversitesi, Istanbul, Turkey; Seeman, Philip, Departments of Psychiatry and Pharmacology, University of Toronto, Toronto, Canada; Erol, Ismail, Department of Biophysics, Bahçeşehir Üniversitesi, Istanbul, Turkey, Department of Chemistry, Gebze Teknik Üniversitesi, Gebze, Turkey; Mestanoglu, Mert, Department of Biophysics, Bahçeşehir Üniversitesi, Istanbul, Turkey; Durdagi, Serdar, Department of Biophysics, Bahçeşehir Üniversitesi, Istanbul, Turkey
    G-protein-coupled receptors (GPCRs) are targets of more than 30% of marketed drugs. Investigation on the GPCRs may shed light on upcoming drug design studies. In the present study, we performed a combination of receptor- and ligand-based analysis targeting the dopamine D2 receptor (D2R). The signaling pathway of D2R activation and the construction of universal pharmacophore models for D2R ligands were also studied. The key amino acids, which contributed to the regular activation of the D2R, were in detail investigated by means of normal mode analysis (NMA). A derived cross-correlation matrix provided us an understanding of the degree of pair residue correlations. Although negative correlations were not observed in the case of the inactive D2R state, a high degree of correlation appeared between the residues in the active state. NMA results showed that the cytoplasmic side of the TM5 plays a significant role in promoting of residue–residue correlations in the active state of D2R. Tracing motions of the amino acids Arg219, Arg220, Val223, Asn224, Lys226, and Ser228 in the position of the TM5 are found to be critical in signal transduction. Complementing the receptor-based modeling, ligand-based modeling was also performed using known D2R ligands. The top-scored pharmacophore models were found as 5-sited (AADPR.671, AADRR.1398, AAPRR.3900, and ADHRR.2864) hypotheses from PHASE modeling from a pool consisting of more than 100 initial candidates. The constructed models using 38 D2R ligands (in the training set) were validated with 15 additional test set compounds. The resulting model correctly predicted the pIC50 values of an additional test set compounds as true unknowns. © 2017 Elsevier B.V., All rights reserved.